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| Titel |
Hydrological processes and water resources management in a dryland environment IV: Long-term groundwater level fluctuations due to variation in rainfall |
| VerfasserIn |
J. A. Butterworth, R. E. Schulze, L. P. Simmonds, P. Moriarty, F. Mugabe |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 3, no. 3 ; Nr. 3, no. 3, S.353-361 |
| Datensatznummer |
250001086
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| Publikation (Nr.) |
 copernicus.org/hess-3-353-1999.pdf |
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| Zusammenfassung |
To evaluate the effects of variations in rainfall on groundwater, long-term
rainfall records were used to simulate groundwater levels over the period
1953-96 at an experimental catchment in south-east Zimbabwe. Two different
modelling methods were adopted. Firstly, a soil water balance model (ACRU)
simulated drainage from daily rainfall and evaporative demand; groundwater
levels were predicted as a function of drainage, specific yield and water table
height. Secondly, the cumulative rainfall departure method was used to model
groundwater levels from monthly rainfall. Both methods simulated observed
groundwater levels over the period 1992-96 successfully, and long-term simulated
trends in historical levels were comparable.
Results suggest that large perturbations in groundwater levels area a normal
feature of the response of a shallow aquifer to variations in rainfall.
Long-term trends in groundwater levels are apparent and reflect the effect of
cycles in rainfall. Average end of dry season water levels were simulated to be
almost 3 m higher in the late 1970s compared to those of the early 1990s. The
simulated effect of prolonged low rainfall on groundwater levels was
particularly severe during the period 1981-92 with a series of low recharge
years unprecedented in the earlier record. More recently, above average rainfall
has resulted in generally higher groundwater levels. The modelling methods
described may be applied in the development of guidelines for groundwater
schemes to help ensure safe long-term yields and to predict future stress
on groundwater resources in low rainfall periods; they are being developed to
evaluate the effects of land use and management change on groundwater resources. |
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